The synthesis and processing of nuclear ribosomal RNA (rRNA) and heterogenous RNA (hnRNA) will be studied in vitro in L1210 leukemia cells. (3H)uridine will be used to pulse label and measure the synthesis of various species of nuclear RNA in L1210 cells. The methylation of rRNA and hnRNA, as well as the polyadenylation of hnRNA will be examined in representative post-transcriptional processes. The nucleoside anticancer agents, cordycepin (3'-deoxyadenosine) and xylosyladenine will be used to examine their specific inhibitory action on rRNA, poly(A), non-poly(A)hnRNA and poly(A)hnRNA synthesis in the presence and absence of the adenosine deaminase inhibitor, 2'-deoxycoformycin.